Some engines include a variable valve train module which controls valve lift through hydraulic operation. This module can include a valve control block positioned on one or more cylinder heads of an engine. The valve control block can include various spaces for components and cavities for hydraulic fluid which together control valve timing and lift. For example, the valve control block may include a pump which pressurizes a cavity connected to a valve actuator, providing valve lift event control in a manner which benefits engine efficiency (e.g., through variable valve actuation depending on the situation).
Implementation of a hydraulic variable valve train system can sometimes eliminate a traditional intake camshaft. In its place, an exhaust camshaft which is external to the valve control block may be positioned for interaction with the variable valve train system components. However, in some instances it is beneficial to include the intake camshaft within the hydraulic variable valve train module. This could cut down on the additional space that is added by the system and allow it to be more easily used in conjunction with certain types of engines, including overhead camshaft engines.
An example of an overhead camshaft engine is described in U.S. Pat. No. 4,593,657 (“the '657 patent”). The '657 patent includes a camshaft which is integrated with and supported by the cylinder heads of the engine. In particular, integrated support bearings are built into the structure of the cylinder heads for supporting the camshaft. This type of engine could benefit from a hydraulic valve train system, but it may be difficult to do so without removing the camshaft. Moreover, the type of bearing support used in the '657 patent could be improved as they do not allow for ease of access to nearby components (e.g., within the cylinder head).
The present disclosure is directed to overcoming one or more problems of the prior art, including the application of a variable valve timing block which works in conjunction with the intake camshaft and solidly supporting the camshaft while providing access to the nearby components.